Dock insert



FIG. 1 is a top rear perspective view of a dock insert showing our new design;

FIG. 2 is a bottom rear perspective view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines in the Figures show portions of the dock insert which form no part of the claimed design. 

The ornamental design for a dock insert, as shown and described. 